RE: grinding noise
it could be either diff. if you haven't already tear it apart down to the diffs and look at the gears on the diff and the bevel gear(little gear on the shaft) and see if they are sharp and pointy on everysingle tooth, if even a couple are dull or stripped then that could be the problem, also i would suggest that you rebuild the diffs. both of those were the problem on mine a long time ago. i would suggest you do both.